CASE REPORT Open Access

Progression of retinal pigmentationmimicking unilateral retinitis pigmentosaafter bilateral pars planitis: a case reportJosé I. Vela1,2* , Ivanna Marcantonio1, Jesús Díaz-Cascajosa1, Jaume Crespí1,2 and José A. Buil1

Abstract

Background: To report our findings in a young patient with unilateral retinitis pigmentosa (RP)-like appearancewho developed pigmentary changes in his left retina after an episode of bilateral pars planitis.

Case presentation: A 17-year-old man presented with 6 months of blurry vision in both eyes. He was diagnosedwith bilateral pars planitis. Progressive, intraretinal bone crepuscule pigmentation developed in his left retina duringthe following three months. An electroretinogram showed subnormal response only in the left eye, suggesting thediagnosis of unilateral pseudoRP.

Conclusion: An inflammatory disease like pars planitis can accelerate the pigmentation of the retina and mimic a RPin young patients. Causes of pseudoRP may be considered, especially in those rare cases with unilateral affection.

Keywords: Pars planitis, Pigmentation, Pseudoretinosis, Unilateral retinitis pigmentosa

BackgroundRetinitis pigmentosa (RP) refers to a group of inherited dis-eases causing retinal degeneration. It is a major cause ofvisual disturbance and blindness in all age groups. It usuallycomes with a bilateral, symmetric impairment of visualfunctions along with night blindness and gradually concen-tric loss of peripheral vision [1]. However, unilateral caseshave been described as a rare manifestation form of RP [2].Retinal pigmentary changes as coarse clumps in a “bone

spicule” configuration are typically observed in RP, butfundus appearance depends on the stage of retinal degen-eration. In the earliest stages, especially in young patientswithout symptoms, the fundus usually appears normaland the diagnosis may be delayed. When no pigmentationis observed in the fundus despite documented abnormal-ities of retinal cell function, the term RP sine pigmento hasbeen used [3].Some disorders as melanoma of the choroid can lead to

retinal changes with pigment irregularities, mimicking RP

[4]. Few inflammatory eye diseases like congenital infec-tions have been described, causing a fundus appearancesimilar to RP. In all of these cases (lupus, Fuchs’ hetero-chromic iridocyclitis, syphilis, toxoplasmosis, cytomegalo-virus, rubella, measles or diffuse unilateral subacuteneuroretinitis) RP must be ruled out [5, 6].We present a case of a young patient who quickly de-

veloped pigmentary changes in his left retina mimickinga unilateral RP after an episode of bilateral pars planitis.

Case presentationA 17-year-old man with no known past medical history,presented with 6 months of blurry vision in both eyes.He had no other ocular, medical, or surgical history.Baseline visual acuity (VA) was 20/20 in the right eye

(RE) and 20/63 in the left eye (LE). His intraocular pres-sure was normal (17/16 mmHg). Slit lamp examinationrevealed normal anterior structures and no anterior seg-ment inflammation. A subclinical keratoconus was de-scribed in the topography study. 1+ cells in the vitreous(graded on a scale of 0+ to 4+), snowballs and snowbanking in the inferior pars plana as well as peripheralvasculitis were observed in both eyes (BE) on dilatedfundus examination.

* Correspondence: 34128jvs@gmail.com1Department of Ophthalmology, Hospital de la Santa Creu i de Sant Pau,Barcelona, Spain2Department of Ophthalmology, Institut Condal d’Oftalmología, Barcelona,Spain

© The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Vela et al. BMC Ophthalmology (2018) 18:242 https://doi.org/10.1186/s12886-018-0814-2

Serological tests for HIV, Toxoplasma gondii, Borreliaburgdorferi or Treponema pallidum were negative, aswell as for antinuclear (ANA) and antineutrophil cyto-plasmatic (ANCA) antibodies.He was diagnosed with bilateral pars planitis. Optical

coherence tomography (OCT) showed cystoid macularedema in the LE, so that sub-tenon injection of triam-cinolone was performed in order to control inflamma-tion, which was slowly reduced.Subsequent follow-up visits showed improvement in

vision to 20/25 in the LE, resolving progressively the in-flammation of the posterior pole although 0.5+ cellswere observed in the vitreous cavity. Then, no additionaltherapy was needed. Nonetheless, the patient com-plained of loss of visual field in his LE.In-depth fundus examination showed a mild, diffuse,

granular appearance of the retinal pigment epithelium(RPE) throughout the LE. Progressive, intraretinal bonecrepuscule pigmentation developed during the followingthree months (Fig. 1). The RE showed no retinal pig-mentation. Humphrey perimetry confirmed periphericconstriction of the visual field in the LE and no scot-omas in the RE.An electroretinogram (ERG) showed subnormal re-

sponse only in the LE. The diagnosis of unilateralRP-like appearance was made.

Discussion and conclusionsWe report a rare case of pars planitis with progressiveunilateral pigmentation of the retina. Unilateral RP(also called extremely asymmetrical RP) is a rare andcontroversial condition that has been described in theliterature, but there are still doubts about its existenceas an isolated clinical entity and its relation to RP.Some mechanisms purposed are the occurrence of gen-etic mosaics (mutations that affect only some of thecells) or somatic mutations (instead of germline muta-tions) [7, 8]. Since retinal dystrophies are usually bilat-eral due to their genetic background, a unilateralmanifestation requires rule out other explanations.

The differential diagnosis for unilateral retinal pigmentepithelium changes and peripheral field loss starts withasking for prior blunt trauma, retinal detachment orretained metallic intraocular foreign body. Treatment withantipsychotics from the group of phenothiazines can in-duce a peripheral pigmentary retinopathy [9]. Since ourpatient had no history of trauma or consumption of anti-psychotics, this differential diagnosis could be excluded.Some patients with cancer can develop antibodies

against retinal antigens (antirecoverin antibodies), leadingto a paraneoplastic syndrome called carcinoma-associatedretinopathy or autoimmune retinopathy [10]. Since theautoantibodies circulate in the blood stream, BE are usu-ally affected.Retinal pigmentary changes can also occur in the con-

text of past ocular infection or inflammatory eye disease.Syphilis, toxoplasmosis, cytomegalovirus, rubella, mea-sles or diffuse unilateral subacute neuroretinitis (DUSN)must be ruled out [6]. They can occur uni or bilaterally,usually early in life. As described above, infections wereexcluded in our patient.The patient was first diagnosed of pars planitis. Few

publications of uveitis coexisting with RP have beenreported, specially a form of non-granulomatous uve-itis called Fuchs’ heterochromic iridocyclitis [11–14].Dust-like particles in the vitreous are present in thegreat majority of young individuals with RP. Theseusually are fine, colorless particles comprising freemelanin pigment granules, uveal melanocytes, EPRcells, and macrophage-like cells. These particles canbe confused with vitreous cells or snowballs presentin the intermediate uveitis. Particles in RP eyes areevenly distributed throughout the vitreous while thesnowballs, larger in size, are observed at the bottomof the vitreous cavity. Observation of these small par-ticles can be helpful in the diagnosis of early RP be-fore pigmentary fundus changes are apparent. Ourpatient showed vitreous cells and snowballs in BE sothat the observation of these dust-like particles in theLE was difficult.

Fig. 1 a Colour fundus photograph (superior field) of the left eye showing mild RPE mottling, blurred by vitreous cells. Retinal pigment depositswere not observed. b Pigmentation of the retina developed three months after onset

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The typical bone-spicule pigmentation represents mi-gration of pigment into the interstitial spaces of the ret-ina from disintegration of RPE cells. This pigmentaccumulation is greater in the surrounding spaces of theretinal vessels, producing perivascular pigmentary cuff-ing and spicule-shaped deposits. Almost all forms of RPgo through a stage where no pigmentary changes existin the retina. This stage may exist for decades beforetypical RP signs appear.Pigmentation of the retina developed in only three

months in our patient. Probably some grade of epithelitisdeveloped in the left eye of our patient. We hypothesizethat inflammation may accelerate the pass to the pigmen-tary stage. It is well known that inflammatory eye diseaseslike rubella, syphilis or DUSN present with pigmentary ab-normalities within the retina [6]. Inflammation can pro-mote a RPE cell reaction and stimulate the migration ofthe pigment into the retina. The pigment deposits areclumps or large patches of black pigment and can be asso-ciated to chorioretinal scars. Then, distribution of pigmen-tation due to inflammation is usually patched and typicalbone-spicule pigment formations are uncommon.In summary, an inflammatory process like pars planitis

can accelerate the pigmentation of the retina. Asymmet-rical RP must be ruled out in these unilateral RP-like ap-pearance post-inflammatory changes.

AbbreviationsBE: Both eyes; ERG: Electroretinogram; LE: Left eye; RE: Right eye; RP: Retinitispigmentosa; RPE: Retinal pigment epitelium; VA: Visual acuity

AcknowledgementsThis case report was supported by the Department of Ophthalmology, SantPau Hospital. We would like to thank Fernando Sánchez for his expertisewith ocular imaging.

Availability of data and materialsThe datasets used and/or analysed during the current study are availablefrom the corresponding author on reasonable request.

Authors’ contributionsJV clinically assessed, analyzed and interpreted the patient data regardingthe ocular manifestations. JV and IM were major contributors in writing themanuscript. JD and JC compiled patient data. All authors read and approvedthe final manuscript.

Ethics approval and consent to participateNot applicable.

Consent for publicationWritten informed consent was obtained from the patient for publication ofthis case report and accompanying images. Written informed consent wasalso obtained from his parents.

Competing interestsThe authors declare that they have no competing interests.

Publisher’s NoteSpringer Nature remains neutral with regard to jurisdictional claims inpublished maps and institutional affiliations.

Received: 11 June 2017 Accepted: 8 June 2018

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